1. Field
This application relates to ink-jet printing, more particularly involving print media reuse.
2. Prior Art
The following is a list of some prior art that presently appears relevant:
U.S. PATENTSPat. No.Issue DateName of Patentee5943067Aug. 24, 1999Kong7205088Apr. 17, 2007Iftime7381757Jun. 03, 2008Sato7111933Sep. 26, 2006Morris
U.S. PATENT APPLICATIONSPublication NumberPublication DateName of Applicant20040150702Aug. 05, 2004 Tsuyoshi20090034997Feb. 05, 2009Edwards20070228005Oct. 04, 2007Hasegawa
NON-PATENT LITERATURE DOCUMENTSUser “GLOBALTOURNIQUET”at Halfbakery.com, “Disappearing Toner - Disappearingink for your printer”, posted to www.halfbakery.com/idea/Disappearing_20Toner on May25, 2002MASINO, “Disappearing Ink Inkjet Cartridge”, posted towww.masino.com/ideas/DisappearingInkjet.php, circa 2001
Despite the availability of electronic information displays, the consumption of paper for printing hardcopies continues to increase. Although paper is inexpensive, the quantity of new paper that is used and discarded is enormous and the impact on the environment is significant. Some of the discarded paper is recycled. While an improvement over disposal, recycling nevertheless requires collection, transportation and processing, with associated economic and environmental costs.
A large amount of paper is consumed printing permanent hardcopies in situations where a temporary hardcopy would suffice. Frequently a temporary hardcopy would be adequate for a meeting agenda, a draft of an article, memorandum, or report to be proofread, or recurring information such as daily as schedules or news. It is often helpful to have hardcopy in hand to read but a permanent hardcopy copy of the information is not required. For this reason many paper documents are discarded the same day they are printed.
Several alternative types of print media have been developed to substitute for paper in temporary hardcopies. These media are designed to be erased and reused multiple times. U.S. Pat. No. 5,943,067 to Kong discloses a multi layer print medium that is electrically, magnetically, thermally or similarly activated by a physical effect to change its appearance. U.S. Pat. No. 7,205,088 to Iftime discloses a print medium that changes appearance when exposed to a particular wavelength of light. Similarly U.S. patent application 20090034997 to Edwards discloses a print medium that changes appearance when exposed to light or heat. The substitute print media of Kong, of Iftime, and of Edwards are more costly than paper, are not recyclable at the end of their useful life, and require the purchase and use of special new printing equipment. In addition, erasing devices are typically required to allow reuse of the media.
Another approach has been to develop erasable inks and corresponding erasing devices and procedures to allow the reuse of paper from temporary hardcopies. U.S. Pat. No. 7,381,757 to Sato discloses ink which is visible when printed and erased when the paper is heated. A heating device or procedure is required to erase the ink from the paper before the paper can be reused. U.S. patent application 20040150702 to Tsuyoshi discloses ink which is visible when printed and erased when the paper is illuminated. An illumination device or procedure to un-stack pages of a document and expose each and every sheet to light is required to erase the ink from the paper before the paper can be reused. U.S patent application 20070228005 to Hasegawa discloses a process to apply a special coating to paper, print on the coated paper, and then erase the paper using a reactive gas generated by a creeping discharge or corona discharge machine.
U.S. Pat. No. 7,111,933 to Morris discloses a system in which invisible ink is printed on a substrate and subsequently made visible by a developer. The disclosed process is the opposite of self-erasing and does not address temporary hardcopies.
Writing pens are available that contain disappearing ink. These are made for humor and entertainment rather than for the reuse of paper. On the Internet, suggestions have been made somewhat facetiously to extend the disappearing ink pen concept to printers. A posting by the user name “GLOBALTOURNIQUET” at www.halfbakery.com/idea/Disappearing—20 Toner asks if disappearing ink is available to hide the evidence that an obscene e-mail message was printed. A posting by Masino at www.masino.com/ideas/DisappearingInkjet.php suggests that a disappearing ink inkjet cartridge would be useful to print disappearing clauses on contracts, or clothing on pornographic images to avoid getting into trouble at work.
From consideration of the foregoing there remains a need to provide a means of printing temporary hardcopies that are familiar in appearance and handling, inexpensive, self-erasing, reusable, and recyclable. There is further need to produce the temporary hardcopies using existing printing equipment.